1. Field of the Invention
The present invention relates generally to a wireless dog tag style apparatus for storing information for being read infrequently such as during emergencies. The invention relates more specifically to a personal information carrier device designed to be worn on a person's body and to be read wirelessly using a nearby reader for extracting selected data from the device. The device remains in an inactivated or “dead” state until it is brought to life when it is interrogated by a coded signal so that its battery retains its charge over very long periods of time.
2. Background Art
The most relevant prior art appears to be issued U.S. Pa. No. 6,747,561 to Reeves. Reeves discloses a bodily worn enclosure having memory capacity to store digitized medical records which may be retrieved using a portable wand reader unit via a so-called optical eye. The data can then be stored in the reader and sent wirelessly to a hospital base unit. One disclosed embodiment of the Reeves patent operates as a completely passive device which does not require a battery or other power source. Instead, this Reeves embodiment operates as an RFID tag to store data. Another Reeves embodiment receives operating power inductively only when being read. A transponder may be employed to emit an AM or FM signal in the event that the wearer of the device is lost and needs to be located. In this case, an on-board long life battery is included.
A disadvantage of relying on a free space optical link to download data from a bodily worn device is that the environment may not be compatible. For example, if the device is worn like a dog tag on a battlefield, there may be mud, sand or other optically obscuring materials which interfere with the optics and make the transfer of data unreliable. A disadvantage of a passive RFID tag in regard to storing data is its limited memory capacity. Large memory content is incompatible with low energy transfer, which is inherent in passive RFID tag technology. Therefore, the use of an entirely passive memory implies low content, small bandwidths and/or slow transfer rates. Inductive power transfer requires relatively large induction coils in both the bodily worn unit and the reader. Such a large coil would require a large package size making it much too large to be a dog-tag-like package.
Thus, there is still a need for a high-content wireless memory device that uses reliable radio frequency wireless data transfer technology, that operates using a battery rather than being an entirely passive device or using inductively transferred power, and which is of sufficiently small size to be worn like a dog-tag or the like. Most significantly, there is a need for such a device which can be expected to operate in an emergency on a battery that is capable of lasting over a period of years with little or no recharging.